Control assembly



3.. J Ar w. J. MUCHER 2,926,323

CONTROL ASSEMBLY Filed Nov. 1:. 1958 Feb. 23, 1960 FIG.

f 7 2% &\\\\\\ IN V EN TOR. N/Z LIAM J. III/(HER K4 4 0M1 M1 HTI'OFNEYS United States Patent CONTROL ASSEMBLY William J. Mucher, Straiford, N.H., assignor to Clarostat glfg. Co., Inc., Dover, N.H., a corporation of New ork Application November 13, 1958, Serial No. 773,694

8 Claims. (Cl. 338-174) This invention relates to a structurally and functionally improved control assembly of the electrical type and by means of which a feel-perceptible structure is embodied in the assembly, such that an operator will have no difficulty in adjusting the parts and sensing when they have assumed predetermined and desired positions with respect to each other. Also, a torque control is embodied in the assembly, such that the latter will properly operate for long periods of time without critical elements of the assembly being subjected to undue wear or distortion.

As is well understood, electrical controls ordinarily are provided with resiliently supported contacts. These assure uninterrupted engagement of the electrical elements as one is traversed over the other. It is found that the optimum contact force in the case of a control involving a resistance ribbon or coarse wires in the order of 0.06 may be around 450 grams. In the case of resistance wires in the order of 0.002" the contact force may approximate 250 grams. Controls of this type frequently have torque requirementsgreater than can be provided by the friction set up between electrical contacting elements.

If an attempt is made to overcome this difficulty by increasing the contact force, the resistance element is subjected to undue wear which will materially shorten the life of the control.

By means of the present teachings, a control assembly is provided in which an improved torque expedient or structure is furnished. This control is, in effect, completely independent of the contacting elements forming a part of the assembly. Therefore, any desired torque value may be embodied in the control without the parts of the latter being subjected to undue Wear.

Additionally, the arrangement of the parts will be such that the concentric relationship of the same is enhanced to thus prevent uneven actuation and wear of the parts resulting in premature failure.

With these and other objects in mind, reference is had to the attached sheet of drawings illustrating one practical improvement of the invention and in which:

Figure 1 is a face view of a control assembly;

Figure 2 is a sectional side view taken along the line 22 in the direction of the arrows as indicated in Figure 1;

Figure 3 is a fragmentary transverse sectional view taken along the line 33 in the direction of the arrows as indicated in Figure 2; and

Figure 4 is a perspective view of the control shaft and detent base elements in separated condition.

For the purposes of simply illustrating the structure herein involved, one form of control embodying a potentiometer structure has been shown. This, however, is to be regarded in an illustrative rather than a limiting sense in that structures achieving the desired functional results herein accomplished might easily be combined with other types of controls as well as with controls including materially different structures. Thus, attention is primarily directed to Figures 1 and 2 of the drawings.

In those views the numeral 5 indicates a casing or mounting structure preferably formed of dielectric material and which supports a resistance 6 coiled upon a strip 7. The latter is conveniently received within a recess formed in body 5. In accordance with conventional structures a bushing 8 may extend from body 5 and rotatably support a shaft 9. The latter-When properly disposed with respect to the bushing-has its annular groove 10 retaining a 0 ring or equivalent element 11. This bears against the end of bushing 8 and prevents inward movement of the shaft 9 with respect to the same.

Also in accordance with conventional teachings, the outer end of this shaft may support a knob (not shown) by means of which it is conveniently turned. Bushing 8 may extend through an opening in a control or mounting panel and support upon its outer face a clamping nut which will retain the assembly in proper association with that mounting. The inner end of shaft 9 as illustrated may terminate adjacent the inner face of the control casing or body 5 and support a suitable contact.

Such an arrangement is illustrated in the prior United States patent to George J. Mucher, 2,836,689 of May 27, 1958, and in which the inner end of shaft 9 terminates in a noncircular portion 12 extending through a contactsupporting assembly. That assembly may include an outer washer 13 of metal bearing against a plate 14 of insulating material to which there is secured a contact carrier in the form of a ring 15. The connection between the parts is conveniently established by rivets 16. interposed between the face of plate 14 and the shoulder defining the inner end of shaft 9 is the base of a stop element in the form of a plate 17. This plate extends rearwardly as at 18 to contact stop 29 in the well or space defined in body 5.

Various other configurations than a ring might be employed for mounting the contact. However, such a structure is in many respects preferred with the plate 14 being of substantially semi-circular configuration. With the parts thus defined, the extended portion of the carrier ring 15 may terminate in a support and retaining portion 19. That portion, together with the adjacent parts of ring 15, serves to support contact element 20. Such element rides in engagement with the outer zone of the resistance path 6 and bridges the space between that path and a contact ring 21. Thus, as shaft 9 is turned, contact element 20 will ride in engagement with these parts.

Ring 21 extends around the shoulder defining the space between the well of body 5 and the rear face of that body. Retaining extensions 21 are conveniently provided integral with ring 21 and bear against the side face of the well or recesses. A strip 22 of insulating material is preferably disposed between the rearwardly extending portion of ring 21 and the rear face of body 5. With a control of the type illustrated, terminals 23 may be electrically connected one to each of the ends of the resistance. A further terminal 24 extends from and may be integral with ring 21. The rear face of body 5 is conveniently grooved as at 25 to accommodate terminal 24.

Disposed adjacent the inner end of bushing 8 and in contact with the base face of the well is a detent plate 26. This plate is centrally apertured and may be inwardly displaced, as at 27, adjacent that aperture. The diameter of the latter is such that shaft 9 may readily pass therethrough. Plate 26 is formed with a notch 28 accommodating a stop and positioning projection 29 which is integral with body 5. A further notch 30 is preferably formed in the plate. If desired, additional notches or recesses of this type may also be thus formed in that plate for purposes hereinafter brought out.

Secured against movement with respect to shaft 9 is a. detent element illustrated to best advantage in, Figures 3 and 4. As shown, this element may include a body 31, the base of'which is notched as at 32 and from which there extends a resilient projection portion 33. The ra dius ofthis portion is. less than the radius of plate 26. and a bearing projection 33' is conveniently provided at: its outer end. Similar projections 34 are embodied inits. base part.

Thus, if the: shaft is positioned as illustrated in Figure 2, projection 33 will ride in contact with the main face of plate 26. Projections 34' will ride adjacent the raised or deflect portion. 27' of plate 26.. Due to the resiliency embodied in themounting of part 33, traction will be exerted on shaft 9 to maintain the retaining element 11 of the. latter in engagement with the outer edge of bushing 8; This traction will, of course, be enhanced due to the resilient mounting of contact. 29, which yieldingly bears against the resistance 6 and ring 21.

As will be. seen, especially from Figure 3, shaft 9 is formed with slots in its opposed faces which receive the edge zones of the notched portion 32. In. this manner, the torque and detent member 31 is secured against axial movements with respect to the shaft and is also retained against turning with reference thereto. Accordingly, as the shaft isrotated, thebearing part 33 will ride adjacent the outer edge of the bearing member or plate 26 and through. the recess of notch 30. As before brought out, any number of these recesses may be provided at desired points so that an operator, in turning the shaft, will sense the fact that contact 20 is in a certain predetermined position withrespect to resistance 6. At its extremes of rotation, the zone bearing part 33 will engage with the abutmentor boss 29 to interrupt further rotation. The bearing parts 34 will ride adjacent the inner edge of the plate member 26.

From the foregoing, it will be apparent that a detent and torque structure is'embodied in the control assembly without in any way wearing or otherwise detrimentally effecting a contact such as 20. The detent structure being located adjacent the base of the well or path, not alone helps to control the torque, but also-being adjacent the bushingresults in a far more desirable assembly. than has heretofore been provided. It is apparent that the positioning of the plate member 26 and cooperating member 31 may be readily effected and without. interference to other parts of the control assembly. So positioned they will remain in place and fully operative throughout the life of the assembly.

Thus, among others, the several objects of the invention as specifically furnished are achieved. Obviously, numerous changes. in structure and rearrangements of the parts may be resorted to without departing from the spirit of the invention asdefined by the claims.

I claim:

1; A control assembly including in combination a casing, a well portion of said casing, a base of said well portion, a plate member fixed with respect to said casing adjacent said base, a shaft rotatably supported by said casing, aslot formed in said shaft, and a detent member cooperating with said plate member formed with an edge portion in contact with the base of said slot to prevent movement of said, detent member with. respect, to. said.

shaft.

2. A control assembly as defined in claim 1, said plate member being substantially rigid and said detent member yieldingly bearing against said plate.

3. A control assembly as defined in claim 2, said plate member being formed with an opening, said shaft passing therethrough and bearing. parts included in said detent member, one of said parts riding in engagement with. said plate adjacent said opening and another of said parts similarly engaging the plate adjacent its outer edge.

4. A control assembly as defined in claim 3, and said plate being formed with arecessed portion adjacent its outer edges and upon which the other of said detent member parts rides. V

5. A control assembly in accordance with claim 4, in which the non-resilient member is in the form of a circular disc. and the slot is radially formed in the disc.

6. A control assembly including in combination a cas-= ing, a shaft rotatably supported by said casing, a circular detent plate fixed with respect to said casing, a centralv aperture of said detent plate through which passes said shaft, a resilient detent element, a bearing portion of said detentelement adjacent said detent plate, a notched portion of said detent element, edge zones of said notched portion, and slots formed in opposed faces of said shaft receiving said edge zones which ride in contact with the base of said slots to prevent movements of said detent element with respect to said shaft.

7. A control assembly including in combination a; casing, a shaft rotatably supported by said casing, a circular detent plate fixed with respect to said casing, :acentral aperture of said detent plate through which passes said shaft, a resilient detent element fixedly supported by: said shaft and relatively rotatable with respect to said casing, a bearing portion of said detent element, a bearing projection of said detent element spaced from said bearing portion, a second bearing projection of said detent element spaced from said first bearing projection and said bearing portion, said bearing portion and said bearing projections yieldingly urged against said detent plateforming a three-point contact therewith.

' 8. A control assembly in accordance with claim 7, in which the detent plate is formed with a portion thereof surrounding the central aperture displaced inwardly. toward the detent element and the bearing portion of the detentelement is in contact with the inwardly displaced portion of the detent plate and the bearing projections of the detent element are in contact with the remaining portions of the detent plate.

References Cited in the file of this patent UNITED STATES PATENTS 

